Catalyst composition for oxychlorinating hydrocarbons and process for preparing the catalyst composition

ABSTRACT

Catalyst composition suitable for the oxychlorination of hydrocarbons. The catalyst composition has superior thermal stability, a long-lasting catalytic activity and essentially consists of cupric chloride and a tantalum fluoride salt which are deposited on a porous carrier.

I United States Patent [151 3,639,270 Koyanagi et al. 1 Feb. 1, 1972 [54] CATALYST COMPOSITION FOR [56] References Cited OXYCHLORINATING HYDROCARBONS AND PROCESS FOR PREPARING THE UN'TED STATES PATENTS CATALYST COMPOSITION 2,206,399 7/1940 Grosvenor ..23/2l9 2,442,285 5/ 1948 Cheney; ..260/652 1 lnvemorsI Shunichi Koymfli; m 8"" Fumio 3,206,5 l7 9/1965 Fenton ..260/656 Akin, of Nllgaw-ken Japan 3,214,481 10/1965 Heinemann.. .252/441 x 73 Assigneez Shin Etsu Chemical Co. Ltd. Tokyo 3,461,084 8/1969 Ll ..252/44l Ja an p Primary Examiner-Daniel E. Wyman Flledl y 1968 Assistant Examiner-Philip M. French [2]] APPLNOJ 730,926 Attorney-McGlew and Toren [57] ABSTRACT [30] Foreign Application Priority Data Catalyst composition suitable for the oxychlorlnatlon of May 23, Japan hydrocarbons The catalyst compqsifion has superior thermal stability, a long-lasting catalytic activity and essentially con- [52] US. Cl ..252/441, 252/442, 260/659 sists f cupric id and a tamamm fl id which are [51 Int. Cl. v ..B0lJ 11/78 deposited on a porous Carrie]: [58] Field oi Search ..252/44l, 442; 260/659 3 Claims, No Drawings CATALYST COMPOSITION FOR OXYCIILORINATING HYDROCARBONS ANDIROCESS FOR PREPARING TI-IE CATALYST COMPOSITION The application also discloses a method of preparing the novel catalyst composition by depositing cupric chloride and tantalum fluoride salt on a porous carrier.

The invention is also concerned with a process for oxychlorinating aliphatic hydrocarbons by passing the hydrocarbons in conjunction with an oxygen-containing gas and hydrogen chloride over the novel catalyst composition. If the hydrocarbon to be chlorinated is of olefinic nature, the reaction temperature should be l50280 C. In respect to paraffinic hydrocarbon, the reaction temperature is preferably 250450 C.

SUMMARY OF THE INVENTION This invention generally relates to catalysts and is particularly directed to a novel catalyst composition suitable for the oxychlorination of aliphatic hydrocarbons, and to a method for preparing such catalyst composition. Considered from another aspect, the invention relates to a process for the oxychlorination of aliphatic hydrocarbons with the novel catalyst composition for the purpose of obtaining chlorinated aliphatic hydrocarbons.

It has previously been suggested to effect oxychlorination of hydrocarbons in the presence of catalysts that contain cupric chloride as the main constituent. A cupric chloride containing catalyst of this nature has thus been disclosed in US. Pat. No. 3,148,515. These known cupric chloride-containing catalysts are, however, not entirely satisfactory because they have the tendency of gradually losing their catalytic activity. The reason for this is that due to the high temperatures which are employed during the oxychlorination reaction, the cupric chloride is slowly volatilized which, in turn, results in reduced catalyst activity. With a view to minimizing this phenomenon, it has been suggested to use the cupric chloride in conjunction with chlorides of alkali metals, selenium, ytterbium, thorium, uranium and didyium or bisulfates such as NaI-ISO,. These attempts, however, have not been successful because, even if such catalyst mixtures are used, the reaction temperature during the oxychlorination reaction must still be kept as high as between 200 and 300 C. which, in turn, results in the occurrence of undesired side reactions which reduce the yield rates of the chlorinated hydrocarbons, to wit, the desired end products. Generally, the use of such known catalyst mixtures and the side reactions resulting from such use, render the refining processes exceedingly complicated. Furthermore, the tendency of the cupric chloride to volatilize is not negated by the admixture of the additional ingredients and the gaseous cupric chloride, in combination with hydrogen chloride and water, cause significant corrosion of the reaction apparatus.

US. Pat. No. 3,010,913 suggests that the HC] conversion may be increased to above 90 percent at relatively low temperature of between 180 and 250 C.; by employing catalysts which are prepared by depositing cupric chloride, dissolved in an alkyl alcohol containing from one to eight carbon atoms, on porous carriers, the cupric chloride being the main constituent of the catalyst. oxychlorination with such catalysts does not result in high yields of chlorinated hydrocarbons and requires complicated refining processes. This prior art procedure is therefore not economically sound.

It is a primary object of the present invention to overcome the prior art disadvantages and drawbacks by providing a cupric chloride-containing catalyst suitable for the oxychlorination of aliphatic hydrocarbons which is possessed of superior thermal stability and which maintains its catalytic activity over long periods of time.

It is also an object of this invention to provide a novel catalyst composition of the indicated nature which renders it possible to obtain chlorinated aliphatic hydrocarbons in high yields and at relatively low reaction temperatures.

A further object of the invention is to provide a novel catalyst composition of the indicated nature which makes it possible to oxychlorinate aliphatic hydrocarbons at low tem peratures and in high yields and without the occurrence of undesired side reactions.

Still another object of the invention is to provide an exceedingly simple process for preparing the novel catalyst comried out without danger of corrosion of the reaction apparatus.

Briefly, and in accordance with this invention, the novel catalyst composition e entially consists of a porous carrier having incorporated therein cupric chloride and at leat one tantalum fluoride salt. The catalyst composition is prepared by depositing a mixture of the cupric chloride and the tantalum fluoride salt on the porous carrier.

oxychlorination of aliphatic hydrocarbons with the novel catalyst composition is carried out in accordance with the invention in the vapor phase and in the presence of an oxygen containing gas and hydrogen chloride.

It is well known in the art that cupric chloride catalysts employed in oxychlorination reactions exhibit their greatest activity when they are in a molten state. Since the melting points of prior art cupric chloride catalyst are relatively high, the catalysts had to be maintained at a high temperature with a view to enhancing their catalytic efficiency. By contrast, and in accordance with this invention, it hasbeen found that mixtures of cupric chloride and tantalum fluoride salts have a comparatively low melting point while at the same time exhibiting an extremely high catalytic activity. Accordingly, the novel catalyst composition comprising cupric chloride and a tantalum fluoride salt can be successfully employed for the catalytic oxychlorination of. aliphatic hydrocarbons at relatively low temperatures thereby avoiding the dreaded volatilization of cupric chloride. While the melting point of cupric chloride is 498 C., that of tantalumfluoride is but 96.8 C., so that a mixture of the two salts forms a compound having a low eutectic point which, by properly choosing the mixing ratio of the two salts, can be fixed to a value below l20-130 C.

As previously stated, the mixture of cupric chloride and tantalum fluoride salt is deposited on a porous carrier. The term porous carrier is deemed to mean any suitable well-known porous substance, as, for example, activated alumina, active charcoal, silica gel, brick, pumice and diatomaceous earth, which thus serves as carrier during the oxychlorination reaction.

The mixing ratio of the components cupric chloride and tantalum fluoride salt should be about between 1:20 and 50:1 by molar ratio in order to give the optimum effect during the oxychlorination reaction. The preferred ratio is between about 1:1 and 5:1 by molarratio. The concentration of the mixture deposited on the porous carrier is also of importance and should be from 1 to 40 weight percent cupric chloride calculated on weight percent of the porous carrier. Nonadherence to the ratios given above does not result in sufficiently economical reaction rates. For example, if the concentration of cupric chloride in the mixture is below 1 percent by weight, the reaction rate will be too low so as to yield any satisfactory industrial advantage. By contrast, if the cupric chloride amount is above 40 percent by weight, the surface area of the porous carrier will become too small, which in turn results in a reduction of the catalytic activity.

From a technical point of view, the mixture of CuCl, and Tab, is advantageously deposited on the porous carrier by dissolving the two salts in water and dipping the porous carrier into the aqueous solution. The porous carrier is then removed from the solution and subjected to drying. The solution may also be sprayed or poured on the carrier material. If necessary, heating of the carrier may be effected to accelerate the drying.

The solvent for the two salts need not, however, be water since organic solvents such as alcohol, for example, ethyl alcohol, may be used. in some instances, it may be advantageous to blend the porous carrier with a powdered mixture of the two lustration and not by way of limitation and that many changes may be effected without affecting the scope and spirit of this invention as recited in the appended claims.

in the examples, the term "HCl conversion" means the rate salts, to wit, the cupric chloride and the tantalum fluoride, and 5 of hydrogen chloride consumed to hydrogen chloride supplied slightly to compress the resulting mass into a self-supporting and EDC selectivity means the mole percent of 1,2- body. The catalyst composition exhibits high catalyst activity dichloroethane to chlorinated hydrocarbons prepared by the and extreme stability. its thermal characteristics are excellent. reaction.

As previously stated, one of the components of the catalyst composition is a tantalum fluoride salt. Tantalum fluoride EXAMPLES proper yields excellent results and may therefore primarily be used, but other tantalum fluoride salts may also be employed. Five different Catalysts, 8nd Thus tantalum fluoride containing complex salts such as tanp p The preparation of 08ml!!! Y f f 3) talum potassium fluoride and tantalum sodium fluoride may depositing the respective catalytic composition indicated in advantageously be used for the inventive purposes. Mixtures table 1 100 8- of activatcd alumlna- The p l of different tantalum fluoride salts are also suitable. Thus, for fected y P g an aqueous of example, a mixture of tantalum fluoride proper and tantalum the activated alumina and subleqmm y l- Each. of potassium fluoride and/or tantalum sodium fluoride gives excatalysts thus prepared was put in a reaction tube and main cellent results. tained at 180 C. A mixture of ethylene, hydrogen chloride in the oxychlorination of aliphatic hydrocarbons, the and air was passed over the catalyst in the ratio indicated in aliphatic hydrocarbons, hydrogen chloride and oxygen or an the table at the space velocity of 495 N I/l. cat.hr. to effect the oxygen-containing gas, such as air, are passed in mixture over oxychlorination reaction. For control, purposes, the sarne the catalyst composition of this invention. ifthe hydrocarbons reaction was carried out by employing catalysts which con are of olefinic nature, the reaction temperature during the oxsisted of CuCL, CuCl,-KCl and CuCl NaHSO NH HSQ. ychlorination should be in the range of from l50280 C. The resultsare tabulated in the following table 1.

. TABLE 1 Example Control Compositions of catalysts 1 2 3 4 5 1 2 3 CuCla (mole).

TaF (mole)- KzT8F7 (mole).

Activated alumina (g.). 100 100 Y 100 100 100 100 100 Reaction temperature C. 180 180 180 180 180 180 180 180 HCl/C1H4 (volume ratio 2 2 2 2 2 2 2 2 Air/01H; (volume ratio)" 5 6 ti 5 5 5 5 5 H01 conversions (percent) 73. 39 68. 27 70. 00 40. 00 75. 30 3. 21 11. 30 32. 00 EDC selectivities (mole percent) 99 20 99 10 99.10 99.21 99.05 98.70 95.10 98.90

referred reaction tern rature ran em from lS0-200 C. If EXAMPLE 6 the temperature is below 150C, the reaction rate will be too low to be economically sound. By contrast, if the temperature is relatively high, to wit, above 280 C., side reactions are liable to take place. For example, in the oxychlorination of ethylene, byproducts such as methyl 'chlori'de, cisand transl ,Z-dichloroethylene, l l ,2-trichloroethane, 1, l ,2,2- tetrachloroethane and trichloroethylene may be produced, lowering the selectivity of 1,2-dichloroethane which is the desired end product.

A suitable mixing ratio for the gases, to wit, olefinic hydrocarbon, hydrogen chloride and oxygen, to be passed over the catalyst composition is about 1:0.5-3 0.1-1 by volume, while the contact time should preferably be from 0.1 to 30 seconds. The reaction may be carried out under any suitable pressure conditions.

The catalysts of the invention may also advantageously be employed iri i the oxychlorination of paraflinic hydrocarbons. in this event, the reaction temperature should be in the range of from 250450 C.' in respect to the mixing ratio of the gases which are passed over the catalyst, the ratio of hydrogen chloride to hydrocarbons may be either increased or decreased in accordance with the kind of chloride which is desired as theend product. However, it is preferred that the volume of oxygen should be larger than that of hydrogen chloride. I a A 1 Whether the hydrocarbons employed as a starting material are .of olefinic or of paraffinic nature, the catalyst will have the greatest effect if the hydrocarbons contain less than four carbon atoms per molecule.

The invention will now be described by several examples, it being understood that these examples are given by way of il- H01 conversion after 60 hours 1101 conversion at the start X Catalyst activity change rate= (1 TABLE 2 Catalyst 0! Catalyst of Example 1 Control 1 Reaction temperature C.) 180 230 180 230 260 Activity change rate (percent).

EXAMPLE 7 The catalyst identified in example 1 was placed in a reaction tube. A mixture of reaction gases consisting of propylene,

hydrogen chloride and air in the volume ratio of l.25:l:2.5 was passed over the catalyst at a space velocity of 505 N Ill. cat.hr. The reaction was carried out at a temperature of 180' C. The C1 conversion was 82 percent, and the reaction product, upon analysis, proved to consist of chlorides of the following composition.

n-propyl chloride 17.0 weight i l,2-dicllloropropane 45.2 weight Iv 1,3-diehloropropane 34.8 weight i allyl chloride 2.1 weight I:

EXAMPLE 8 The catalyst of example 1 was placed in a reaction tube. A mixture of reaction gases consisting of methane, hydrogen chloride and air in the volume ratio of l:2:5.5 was passed over the catalyst at a space velocity of 425 N 1/1. cat.hr. The reaction was carried out at a temperature of 400 C. The HCI conversion was 90 percent and the chloromethanes obtained proved to be of the following composition.

monochloromethane 14.0 weight k dichloromethane 39.2 weight I:

trichloromethane 32.0 weight I;

tetrachloromethane l4.8 weight k EXAMPLE 9 vinyl chloride 42 weight I: monochloroethane 23.2 weight 11 vinylidene chloride l3.2 weight I: l .l-dichloroethane 30.0 weight i:

LZ-dichloroethane 24.0 wei ht b [J ,l-trichloroethane 3.4 weight 1: LI ,Z-triehloroethane 2.0 weight Q:

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. A catalyst suitable for the oxychlorination of aliphatic hydrocarbons, said catalyst essentially consisting of a porous carrier having incorporated therein a mixture of cupric chloride and at least one tantalum salt selected from the group consisting of tantalum fluoride, tantalum potassium fluoride and tantalum sodium fluoride, the molar ratio of said cupric chloride to said tantalum salt being between about l:20 and 50:], said cupric chloride being present in said porous carrier in a concentration of about 1 percent to 40 percent by weight calculated on said carrier.

2. A catalyst as claimed in claim 1, wherein said porous carrier is activated alumina, active charcoal, silica gel, brick, pumice or diatomaceous earth.

3. A catalyst as claimed in claim 1, wherein the molar ratio of cupric chloride to tantalum salt is between izl and 5:1. 

2. A catalyst as claimed in claim 1, wherein said porous carrier is activated alumina, active charcoal, silica gel, brick, pumice or diatomaceous earth.
 3. A catalyst as claimed in claim 1, wherein the molar ratio of cupric chloride to tantalum salt is between 1:1 and 5:1. 